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Future generations could be travelling across the universe faster than the speed of light, without breaking any astronomical road rules, by manipulating extra dimensions of space and time, according to two US physicists.

"We think we can create an effective warp drive, based on general relatively and string theory," says Dr Gerald Cleaver from Baylor University in the US, a coauthor of a paper that recently appeared on ArXiv.org.

The warp engine is based on a design first proposed in 1994 by Dr Michael Alcubierre.

The Alcubierre drive, as it's known, involves expanding the fabric of space behind a ship into a bubble and shrinking space-time in front of the ship. The ship would rest in between the expanding and shrinking space-time, essentially surfing down the side of the bubble.

Travelling without moving

The tricky part is that the ship wouldn't actually move; space itself would move underneath the stationary spacecraft. A beam of light next to the ship would still zoom away, same as it always does, but a beam of light far from the ship would be left behind.

That means that the ship would arrive at its destination faster than a beam of light traveling the same distance, but without violating Einstein's relativity, which says that it would take an infinite amount of energy to accelerate an object with mass to the speed of light, since the ship itself isn't actually moving.

The fabric of space has moved faster than light before, says Cleaver, right after the Big Bang, when the universe expanded faster than the speed of light.

"We're recreating the inflationary period of the universe behind the ship," says Cleaver.

While the theory rests on relatively firm ground, the next question is how do you expand space behind the ship and contract it in front of the ship?

Cleaver and Dr Richard Obousy, the other coauthor, propose manipulating the 11th dimension, a special theoretical construct of m-theory (the offspring of string theory), to create the bubble the ship would surf down.

If the 11th dimension could be shrunk behind the ship it would create a bubble of dark energy, the same dark energy that is causing the universe to speed up as time goes on.

Expanding the 11th dimension in front of the ship would eventually cause it to decrease, although two separate steps are required.

Lots of energy

Exactly how the 11th dimension would be expanded and shrunk is still unknown.

"These calculations are based on some arbitrary advance in technology or some alien technology that would let us manipulate the extra dimension," says Cleaver.

What the scientists were able to estimate was the amount of energy necessary, if the technology was available, to change these dimensions: about 10 to the power of 45 joules.

"That's about the amount of energy you'd get if you converted the entire mass of Jupiter into pure energy via E = mc squared," says Cleaver, an energy far beyond anything humanity can currently envision creating.

While the challenges to creating a warp drive are quite formidable, the concept is intriguing, says Tufts University theoretical physicist Professor Lawrence Ford.

"If there are extra dimensions and we could manipulate them, that would open up all sorts of exciting possibilities," says Ford.

"I don't see this leading immediately to a warp drive, but I could see it leading to other interesting possibilities in basic scientific research," says Ford.

Cleaver agrees that the creation of a real warp drive is still far away.

"Warp drive isn't doable now, and probably won't be for the next several millenia," says Cleaver.